At first glance, it looked like a typical music rehearsal. There at the Colburn School in downtown L.A. were Leann Osterkamp, 22, and Siyi Fang, 25, sitting at pianos playing "Songfest: A Cycle of American Poets" by composer Leonard Bernstein.

It was who was watching them and offering instruction that was unusual.

Hovering nearby was Michael Barrett, a former assistant to Bernstein and the first ever to play the four-hand piano piece with Bernstein. He offered the women advice on how the maestro, who died in 1990, wanted his piece to be played.

Later, awash in layers of musical legacy, Osterkamp, a Boulder, Colo., native, sat in a Colburn auditorium soaking it all in.

"It's really an incredible experience to [learn from] somebody who was really the first generation to know the music directly from Bernstein," Osterkamp said.

She and bands of other young musicians and singers brought in from across North America have filled the auditoriums and stages at the Colburn School for the past week as they began rehearsing for the coincidentally named SongFest 2013 Concert Series. Would-be participants must apply and then audition to win acceptance in the SongFest summer program.

For 18 years the summer music program has welcomed young performers and guest faculty members for a month each summer to study and rehearse before performing a variety of concerts. The program highlights art song and the work of American composers.

From June 28 to July 25, the singers and instrumentalists attend master classes with instructors such as Barrett, composer and pianist John Musto, mezzo soprano Candice Burrows, soprano Lisa Saffer and baritone William Sharp. Concerts are scheduled from July 7 through 24 at Thayer Hall and Zipper Hall in the Colburn School and at the Marina Stage at California Plaza downtown.

Osterkamp and Fang were rehearsing that day for a Bernstein tribute concert deemed "SongFest sings America" that will take place July 13 at California Plaza, co-presented by SongFest& Grand Performances L.A.

Burrows will sing in the program. After performing in "Songfest" at the Tanglewood Music Festival in 1988, she said she is eager to pass on the lessons she learned from the great composer and conductor.

"Bernstein believed that we all have music in us, and he wanted us to believe as musicians that it was worth being heard," Burrows said.

As she recalled her audition for the concert, Burrows laughed. She admitted it had not gone well and that she did not think she would get the part. After she received the surprise call confirming that she would be singing with Bernstein, Burrows asked him why he chose her.

"'Oh, no, you were terrible, but you were the only one who understood the text,'" Burrows recalled him telling her. "'I can teach anyone the tones and rhythms, but I can't teach how to understand the text.'"

She said that lesson, about understanding the meaning of a text, is something she imparts to her students.

Later, Bernstein taught her another lesson. After she'd become accustomed to following his lead, the maestro stepped back during one performance so that when Burrows sang, he was out of her sight. Rather than relying on his direction, she was forced to tap her own knowledge of the music.

"It was magic. After the show he said, 'Every night do something different,'" Burrows said. "'Music is alive and it should never be the same.'"

Jamie Bernstein, Leonard Bernstein's daughter, will narrate the July 13 concert and also is spending time at rehearsals, coaching the young musicians on how her father worked and how he wrote his compositions. She said "Songfest" was based on one of his greatest passions: literature. She joked that although she was an English major in college, Dad possessed a greater knowledge of poetry than she did.

"Everything he did in life was this same impulse to grab your sleeve and say, 'Hey, listen, this is great,'" Jamie Bernstein said.

Barrett, who worked as Leonard Bernstein's assistant for more than six years, said Bernstein's composing and teaching style has not been matched since his passing.

"I don't think there are any conductors that are a humanist on the same level that Lenny was, and he knew so much about so many things," Barrett said.

For Barrett, making connections to the great musicians and composers of the past is important. Just as he was able to link his own piano teacher by a series of earlier teachers all the way back to Beethoven, he said, so it is valuable for people like him to make similar links to younger musicians.

"People of that generation [in their teens and 20s],a lot of them don't really know who Aaron Copland was, they don't really know who George Gershwin was, they're not sure who Duke Ellington was, some of them don't even know who Leonard Bernstein was. They might know 'West Side Story' and that's kind of it," Barrett said. "So there's that huge body of work there for all these people and it's kind of up to us —since the schools don't really do it anymore — to pass that on to the next generation."

Alexandra Smither, a 20-year-old soprano from London, Canada, said that younger generations are seeking these musical legacies. Performing at SongFest last summer, Smither said she had the opportunity to meet and sing with many of her musical heroes.

"These are the people that we're listening to, that we're striving to be like," Smither said.

Osterkamp sat at a café table with Smither and chatted about their eagerness to participate in this year's concert series.

For a moment the smiles subsided and Osterkamp grew serious.

"Right now there is such a cry that classical music and arts song is dying," Osterkamp said, "but this festival, I think, is a really clear picture that there's a lot of hope actually for music, because not only are there a lot of composers here, but there's a generation that's really interested in absorbing it."